• • Doping versus alloying in amorphous MOF precursors leads to distinct reconstruction products: doping yields Fe-rich (oxy)hydroxides with more exposed active sites, while alloying yields Fe-Co mixed (oxy)hydroxides with limited site exposure, directly impacting OER performance.
• • The doped FeCo0.05-PTA catalyst achieves overpotentials of 208 mV at 50 mA cm−2 and 248 mV at 100 mA cm−2, with a Tafel slope of 36.2 mV dec−1, outperforming alloyed counterparts and many reported non-noble OER catalysts.
• • In situ FTIR spectroscopy captured the OOH* intermediate, confirming the adsorbate evolution mechanism (AEM) for OER on these reconstructed catalysts, providing direct mechanistic evidence.
• • DFT calculations reveal the doped system has the lowest free-energy barrier (ΔG = 0.59 eV) at the rate-determining step, correlating with the experimentally observed superior activity and guiding rational catalyst design.